As for the conventional gear of the kind specified, there has so far been known one which is shown, for example, in Japanese Patent Application Laid-open Specification No. 49-89203.
This conventional steering system has been constructed such that a valve spool is axially moved by the rotation of the steering wheel and the fluid under pressure is supplied, at a flow rate corresponding to the amount of movement of the valve spool, from a gyratory rotor into a steering cylinder through a port whose area of opening is controlled by the movement of the above-mentioned valve spool so that a steering operation corresponding to the angle of rotation of the above-mentioned steering wheel may be made by the action of the fluid pressure force.
In the above-mentioned conventional steering system, since an operating force which is approximately proportional to the amount of movement of the valve spool occurs in the steering wheel, when the fluid pressure is increased for operating the steering wheel while the vehicle is stopped or when quick steering is made by turning the wheel quickly, a large steering force is required. Therefore it has been required to improve the operating performance of the steering wheel.
In the meantime, when a reaction force device such as a torsion bar or a leaf spring, is set lightly to improve the above-mentioned disadvantage, disadvantageous phenomena occur. For example, the reaction or response transmitted through the steering wheel when the vehicle is running straight cannot be sensed by the driver thus giving him a sense of unease moreover, the stability of the vehicle when running at high speeds becomes lower.